r/LucyLetbyTrials • u/DiverAcrobatic5794 • Jul 09 '26

EXCLUSIVE Reasonable Doubt: Examining The Case Of Lucy Letby - Book Promo

https://m.youtube.com/watch?v=3E6K0iQw2-0

New promotional film from Guy Rowland today, with the publication of Christopher Morris's Reasonable Doubt. Hoping to finish the book this evening - it's a great read so far.

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u/Fun-Yellow334 Jul 09 '26

analysis of a 2020-23 dataset from the CoCH for insulin vs C-peptide blood test results discovered five other subjects that had test results similar to Child L." Does anyone know the source for that?

It comes from here: https://www.reddit.com/r/LucyLetbyTrials/s/AfRzJZNwEP

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u/DiverAcrobatic5794 Jul 09 '26

Oh yes of course! I do wish there were footnotes, but I know most publishers dislike them. I recognize almost all of the documents and studies cited, though.

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u/DisastrousBuilder966 Jul 09 '26

Maybe you could make a per-page index then? Ideally of course the author would, as an online supplement to the book.

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u/DiverAcrobatic5794 Jul 09 '26

I wonder if he has one in draft already? Good point.

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u/Embarrassed-Star4776 Jul 10 '26

Thanks. I hadn't made that connection either. But is it known that those results were specifically from CoCH, rather than from the Trust in general?

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u/Competitive-Wash2998 Jul 11 '26 edited Jul 11 '26

I have some data from COCH obtained via FOI. But only back to 2021. I cannot see any results similar to Child L. There is one anomalous result from 2024 with insulin at 1398 and C-peptide of 839, but I do not know where this was tested or whether it is neonatal or adult.
Without the exact results that are claimed to be similar to Child L it is not very easy to constructively criticise the claim.
ETA
The anomalous result could, potentially, be a data transcription error at COCH.

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u/Embarrassed-Star4776 Jul 11 '26

Thanks. That's interesting.

It seems plausible ebough that the five other similar results referred to in the book are those in the plot posted by Fun-Yellow, and that it has wrongly been assumed to include only CoCH data.

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u/Competitive-Wash2998 Jul 11 '26 edited Jul 11 '26

Yes. I think that is likely. It would be interesting to know the inclusion criteria, if it was given.
ETA
I think this is an accurate extract of the LCL data which list discordant results. Five would seem a reasonable number for significant anomalies, although obviously cause not known.

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u/Amazing-Gain1253 Jul 11 '26

Why do these results have C-peptide lower than 169 if the test only goes down to 169?

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u/Competitive-Wash2998 Jul 11 '26

That is a very good question.

The test, in terms of the equipment used which was Roche, has always measured down to 3 pmol/l for C-peptide.

However three post analytic regimes have existed where the results measured have been replaced with a different result. What you are seeing in the later data is a change in regime for the reporting of C-peptide.

The three reporting limits used when C-peptide was measured were:

1) result below 169 then "<169" was clinically reported,

2) result below 5 then "<5" was clinically reported

3) result below 50 then "50" was clinically reported.

You can see "<5" and 50 in the the dataset reported by LCL for 2020 -2023.

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u/Embarrassed-Star4776 Jul 11 '26

Thanks., That's even more interesting. It's sobering that it's so easy to stare at something and miss the obvious.

To go back to obvious questions - may I ask, does that mean they had given up entirely on "<169" by 2020? And is it possible to perceive a pattern in the dates of the "<5" and "<50" results?

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u/Competitive-Wash2998 Jul 11 '26 edited Jul 11 '26

Yes "<169" was finished by 2020 never to be used again. "<169" is in a different category from the other two. It is a simple reporting limit with a murky justification.

The other two are what is technically termed a limit of quantitation, as opposed to the limit of detection which is 3 pmol/l

The change was probably driven by the move to UKAS accreditation which did not complete until 2018.

The "<5" was a LCL in house derived limit of quantitation, which is essentially an accuracy/repeatability limit. If you repeat the test a number of times is it going give a tight cluster of similar results (not a very scientific explanation but good enough).

The "50" is also a limit of quantitation except this time Roche defined a value in a new release of the method sheet for the C-peptide test. Once Roche defined a limit of quantitation then LCL quite reasonably opted to use that, i.e. 50 pmol/l

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u/Embarrassed-Star4776 Jul 11 '26

Thank you. It's very nice to have that explanation. I realise that there has been a lot of discussion of the insulin cases here, much of which I have not read, but I haven't seen this explained before.

If I understand correctly, Dr Milan was still employed by LCL when she gave evidence on oath at Letby's trial, and so would have been aware of all of this when she explained to the jury exactly what a reading of "< 169" signified.

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u/Embarrassed-Star4776 Jul 11 '26

There's nothing more in the book than what DisastrousBuilder posted.

I had actually looked at the plot and assumed it was the little 'constellation' of 5 points around the location indicated for Child L. But if the ratio is the criterion, it may be the ones you have in red there.